Heart disease is a significant health problem which has been the subject of substantial medical study. Bypass surgery has become commonplace; yet such surgery may be unavailable to many patients, either because of the nature of the occlusions or the physical condition of the patient.
One promising alternative technique for treating such cases is known as transmyocardial revascularization (TMR). Although this technique was considered as early as the work of Dr. C. Beck "the Development of a New Blood Supply to the Heart By Operation," Annals of Surgery, Vol. 102, No. 5 (11/35) pp. 801-813, the method was not extensively studied until the work of Dr. M. Mirhoseini and M. Cayton, an example of which is found in "Lasers in Cardiothoracic Surgery" in Lasers in General Surgery (Williams and Williams; 1989) pp. 216-223.
Myocardial revascularization systems, used by cardiothoracic surgeons and interventional cardiologists, include a) external- to-the-heart based systems that use either a TMR surgical hand-held instrument or a minimally invasive surgical (MIS)-TMR, both of which create channels from outside the heart into the left ventricle and b) a percutaneous transluminal myocardial revascularization (PTMR) instrument that is a catheter and tissue removal energy delivery system that creates channels partially into the myocardium from inside the left ventricle. In the MIS-TMR procedure, a cardiothoracic surgeon performs a thoracotomy by incision through the chest wall to access the heart using the modified endoscopic surgical instrument containing an internal optical fiber that applies laser energy to the external portions of the heart to create channels through to the left ventricle. In the PTMR procedure, an interventional cardiologist performs a cardiac catheterization procedure using a catheter with an internal optical fiber that is inserted into the femoral artery at the groin and advanced through the heart's aorta arch into the left ventricle. Once in the ventricle, the catheter is guided to the endocardium where the device creates pathways through the endocardium and partially into the myocardium.
TMR, MIS-TMR & PTMR generally require that a physician use a hand-held device that encompasses and guides either a mechanical cutting device or one or more optical fibers through which laser energy is directed. Mechanical or laser energy cuts or vaporizes heart muscle tissue immediately in front of the distal end of the device. From the standpoint of safety and efficacy, the laser TMR procedure minimizes both ancillary tissue damage and embolic material production, both results are highly desirable. Varying penetration depths are possible.
Clinical tests have demonstrated that revascularization channels/pathways, which generally communicate with the ventricle, facilitate revascularization of the heart muscle and recovery of heart function. Recent studies further demonstrate that beneficial revascularization also occurs following creation of channels that do not remain patent and channels that do not communicate with the ventricular chamber. For example, a laser device to perform TMR is described in U.S. Pat. No. 5,380,316 which teaches of a way to form numerous channels through the heart's epicardium through to the heart's ventricle through the myocardium by a laser apparatus. Other patents describing surgical TMR include U.S. Pat. Nos. 4,658,817 and 5,554,152. Lasing through the epicardium or endocardium, as described in many laser TMR procedures, may result in some destruction of viable vascular tissue contiguous to the epicardium or endocardium. Lasing may also produce collateral tissue damage if not carefully controlled.
An alternative to use of lasers in instruments to effectuate revascularization of the heart are mechanical cutter devices to produce these channels. Early prior art methods of mechanical piercing and cutting of the heart wall were not pursued further because mechanical cutting did not produce patent channels.
A recent laser TMR device to perform transmyocardial revascularization includes some non-laser mechanisms and which are taught in PCT Patent Application Publication No. WO 96/35469. This PCT application shows a mechanical auger, mechanical abrasion device, heat, a fluid jet, and a rotary toothed blade for mechanical TMR using a percutaneous approach. The mechanical devices described may produce an irregular cut in the myocardium which may result in leaving tissue flaps or fragments in the channel or ventricle. Such debris can be life threatening due to emboli caused by cut tissue.
U.S. patent application Ser. No. 08/713,531, filed on Sep. 13, 1996, and issues on Feb. 16, 1999 as U.S. Pat. No. 5,871,495 teaches of mechanical TMR using cutting devices comprised of inner hollow needles or drill tipped devices mounted within outer hollow needles for TMR. Additionally, a single rotating, hollow needle is described. A sharp cutting blade is used to produce a clean cut.
U.S. patent application Ser. No. 08/773,778, filed on Dec. 26, 1996, now allowed also teaches of a mechanical cutting device used in conjunction with a laser to create drug delivery pockets and/or stimulation zones within a myocardium. The laser is used to introduce the cutting device into the myocardium, and the cutting device defines two, hollow halves that snap together to cut tissue, which is trapped between the halves, to form pockets.
U.S. patent application Ser. No. 08/908,816, filed on Aug. 8, 1997, entitled Method & Apparatus for Myocardial Revascularization and/or Biopsy of the Heart also describes a semi-automatic cardiac tissue removal device for obtaining biopsy samples and/or creating revascularization pathways in the myocardium of the heart, mechanically cuts the pathways using a hand piece with a cutting tip assembly having a hollow needle with an angled, sharpened edge rotatable mounted around a separately advancable stylet. The stylet defines a piercer to spread the myocardium prior to insertion of the needle and to allow creation of a pathway only within the myocardium. The stylet further defines a plug at the cutting edge of the needle to finish the cutting cleanly and to plug the hollow needle thereby forming a closed chamber for excised tissue.
It is desirable to produce clear, clean revascularization pathways that may be formed only in myocardium, if desired, while ensuring that excised tissue is cleanly removed without leaving tissue flaps and debris behind, using a relatively inexpensive and easily transportable mechanical/laser heart surgical device suitable for heart myocardial revascularization. A design and method that resolves this problem is taught herein for both surgical myocardial revascularization and PTMR procedures.
Moreover, it would be desirable to optionally include a laser vaporization device in such a mechanical coring device with a way for in-situ vaporization of cored tissue which obviates a procedural step of device retrieval from a patient to remove cored tissue from the device distal section.